Method and apparatus for bonding brake shoe and lining

ABSTRACT

A thermal bonding method wherein at least two members are thermally bonded to each other with an adhesive by pressing and heating a laminate formed by laminating at least two members on each other with the adhesive interposed therebetween, comprising placing at least one member of the laminate close to a heated radiation heater and pressing the laminate in a radiation heat-applied state; and an apparatus comprising a radiation heater, a supporting member for supporting the laminate with at least one member of the laminate placed close to the radiation heater, and a pressing unit adapted to approach, contact and press the laminate supported by the supporting member and then move away from the laminate to stop applying a pressure to the same.

TECHNICAL FIELD

The invention relates to a thermal bonding method and an apparatus forthe method. Particularly, it relates to a thermal bonding method and anapparatus for bonding two members laminated with an adhesive interposedtherebetween by heating and pressing, which enable uniform and efficientheating and continuously bonding plural sets of members, and aretherefore excellent in bonding accuracy and cost.

BACKGROUND ART

Conventionally, bonding two members with an adhesive has been performedby a thermal bonding method wherein two members are laminated with anadhesive interposed therebetween into one body which is then pressedwith a jig and passed through a tunnel-like heating furnace while beingpressing continuously to thermally melt or thermally cure the adhesivein the heating furnace.

For example, in production of brake shoe assemblies for drum brakes,bonding brake shoe bodies and friction linings with adhesives has beenperformed by coating a brake shoe body and a friction lining with athermosetting adhesive, drying, setting them in a pressing jig, and thenheating in a thermally curing furnace with hot blast to cure thethermosetting adhesive.

However, thermally curing thermosetting adhesives with hot blastinvolves the problems that quick curing is difficult due to the low heattransfer, and that it cannot heat the parts coated with adhesivesefficiently, because other parts, such as jigs, transfer instruments andthe walls of the furnace, are also inevitably heated. To solve suchproblems and achieve downsizing of equipment and quicker heating, theuse of high-frequency induction heating is proposed in Japanese PatentApplication Non-examined Publication No. 61-153026. The method enablesquicker heating, but is poor in heating efficiency because it is anindirect heating using an eddy current. Another shortcoming is that themethod needs coils and equipment of complicated structures to uniformlyheat brake shoe bodies of complicated shapes.

In Japanese Patent Application Non-examined Publication No. 9-48953disclosed is another bonding method wherein while pressure is beingapplied, one of the members to be bonded is placed in contact with aheated holder to heat it by heat conduction from the holder. In thismethod, bonding with heat and pressure is performed quickly andefficiently. However, in cases where the surface of the member to bebonded by the method is coated with a coating, such as a primer forcoating the surfaces of brake shoes, there arises problems in that thecoating transfers to the holder during thermal curing and is peeled offfrom the product.

In Japanese Patent Application Non-examined Publication No. 9-144793disclosed is another method of bonding a brake shoe body with a frictionlining by laminating them with an adhesive interposed therebetween andthen bonding with heat and pressure, wherein the heat for bonding isgenerated by the brake shoe body itself by electrically charging thebrake shoe body through electrodes pressed to both ends of the brakeshoe body. However, to heat the brake shoe uniformly by this method,complicated control is required, for example, cooling the electrodes andthe parts not bearing the friction lining, or adjusting the pressure tothe electrodes to prevent partial overheat due to contact resistance.Further, adhesives generate gas during cure with heat, and, in thismethod wherein only the electrically charged brake shoe body generatesheat, the gas is cooled and condensed, adhering to the electrodes orjigs. In addition, the method efficiently reduces the heating time, butnecessitates preparation of many apparatuses since the complicatedheating system permits only one laminate to be bonded by one apparatus.

DISCLOSURE OF INVENTION

The object of the invention is to provide a thermal bonding method andan apparatus for the method which enable quick and thermally efficientbonding with heat and pressure using adhesive, such as bonding shoe rimsof brake shoe bodies with friction linings, prevent peeling of surfacecoating, and enable continuous production of plural bonding productsusing simple instrument.

After study to solve the above-described problems, the inventors haveaccomplished the invention based on the finding that the problems can besolved by using radiant heat as the heat for bonding with heat andpressure.

Accordingly, the invention provides a thermal bonding method for bondingat least two members to each other with an adhesive by pressing andheating a laminate formed by laminating the members on each other withthe adhesive interposed therebetween, comprising placing at least onemember of the laminate close to a heated radiation heater and pressingthe laminate in a radiant heat-applied state.

The method of the invention does not need adjustment of pressure norpartial cooling for temperature control, and the simplified heatingprocedure reduces the production cost. It also prevents peeling of thecoating on laminates, because the laminate is not heated by heatconduction but by radiant heat requiring no contact with heaters.Further, since radiant heat also gives a high temperature atmosphere,the gas generating from the adhesive on curing does not condense toadhere to the apparatus. In addition, since the method of the inventionis feasible with apparatuses of simple structures, apparatuses forsimultaneous bonding of plural laminates can be constructed easily,thereby improving the production efficiency.

The invention also provides an apparatus for bonding at least twomembers to each other with an adhesive by pressing and heating alaminate comprising the two members and the adhesive interposed betweenthe two members, which apparatus comprises a radiation heater, asupporting member for supporting the laminate with at least one memberplaced close to the radiation heater, and a pressing unit adapted toapproach, contact and press the laminate supported on the supportingmember and then move away from the laminate to stop applying a pressureto the laminate.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a perspective view illustrating a method and an apparatus ofan embodiment according to the invention.

FIG. 2 is a cross-section illustrating a laminate being thermally bondedby the method and apparatus as shown in FIG. 1.

FIG. 3 is a plan view of the heater in the apparatus of FIG. 1.

FIG. 4 is a partially elevational view of a laminate holder of anapparatus of an embodiment according to the invention.

FIG. 5 is a partial cross-section of a laminate holder of an apparatusof an embodiment according to the invention.

FIG. 6 is a partial side view of the laminate holder of FIG. 4 and FIG.5 which is not yet be machined to make holes.

FIG. 7 is a partial side view illustrating the laminate holder of FIG. 5being fabricated.

FIG. 8 is a perspective view of a pin of an example usable for thelaminate holder of FIG. 5.

FIG. 9 is a partially elevational view of a laminate holder in anapparatus of an embodiment according to the invention.

FIG. 10 is a partial top view of the laminate holder of FIG. 9.

FIG. 11 is a partially elevational view of the laminate holder of FIG. 9having projections made by inserting pins in holes.

FIG. 12 is a cross-section illustrating a method and an apparatus ofanother embodiment according to the invention.

FIG. 13 is a perspective view of a laminate of an example used in themethod of the invention.

FIG. 14 is a top view of the laminate of FIG. 13.

FIG. 15 is a cross-section illustrating the laminate of FIG. 13 beingheated.

BEST MODE FOR CARRYING OUT THE INVENTION

The structure and material of the radiation heater to be used in thethermal bonding method and apparatus of the invention may be of anystructure and any material so far as it can be brought close to at leastone member of the laminate and can emit radiant heat and transfer it tothe member uniformly. Typical examples are heaters which have a housingformed of metal of high thermal conductivity, such as iron, steel,aluminum, stainless steel, aluminum alloy, brass or copper, for example,an aluminum-cast heater, an induction heating plate, a heater housing acartridge heater and a far-infrared heater. It is also possible to heata thermal medium charged in a housing, or to electrically charge a metalcapable of generating heat by using a slip ring so that the metal itselfgenerates heat. Also the shape of the radiant heater is not particularlylimited so far as at least one member of the laminate can be broughtclose to the radiant heater, and may be properly designed depending onthe shape of the laminate. The surface of the radiation heater ispreferably coated with a black coating to improve radiation efficiency.

Further, the radiation heater may comprise a heater and a laminateholder, wherein the laminate holder is in contact with the heater andemits the heat transferred from the heater by conduction. In thisembodiment, at least one member of the laminate is supported close tothe laminate holder, and heated by a radiant heat emitted from thelaminate holder heated by the heater through heat conduction. Examplesof heaters suited to this embodiment include the above-described heaterhaving metal housing, and the heater that emits the heat generated byheating a thermal medium charged in a housing. This method reduces theproduction cost because the heater itself needn't be constructed into acomplicated shape to adapt it to the laminate. It also improves theproduction efficiency since plural laminates can be bonded at a time byeasily mounting plural laminate holders in contact with one heater.

The shape of the laminate holder is not particularly limited as far asat least one member of the laminate can be placed close to the laminateholder, and may be designed properly depending on the shape of thelaminate. The material of the laminate holder is not particularlylimited so far as it can be heated by the heater through heatconduction, and generally preferred is a metal, such as iron, steel,stainless steel, aluminum or aluminum alloy. The surface of the laminateholder is preferably coated with a black coating to improve theradiation efficiency.

The method of supporting the laminate close to the radiation heater (orthe laminate holder of the radiation heater) is not particularlylimited. For example, the face of the radiation heater (or of thelaminate holder of the radiation heater) to be brought close to thelaminate may have parts coming in contact with the laminate to supportit, for example, projections formed on the face. In such an embodiment,it is necessary to minimize the contact area between the radiationheater (or the laminate holder of the radiation heater) and the laminateto heat at least one member of the laminate uniformly and to prevent thetransfer of the coating on the laminate, and the laminate is preferablysupported by point-contact or line-contact. To prevent the coating onthe brake shoe body from transferring to the projections, theprojections may be coated with a releasable heat resistant polymer.

Examples of the releasable heat resistant polymer for coating thesurface of the shoe rim supporter include silicone rubbers, siliconeresins, fluororubbers and fluorocarbon resins.

Examples of silicone rubbers include those produced from anorganopolysiloxane, such as dimethylpolysiloxane raw rubber,methylphenylpolysiloxane raw rubber, methylvinylpolysiloxane raw rubber,cyano, alkylmethylpolysiloxane rubber or fluoroalkyl, methyl,polysiloxane raw rubber, by vulcanizing it with a vulcanizing agent,such as an organic peroxide. These may be compounded with an inorganicfiller, such as silica powder, silica aerogel, calcined diatomaceoussilica, calcined kaolin, calcium carbonate, iron oxide powder, zirconiumsilicate powder, titanium oxide powder or zinc oxide powder. Additives,such as zirconyl nitrate, metal zirconates, zirconium silicate, carbonblack or Teflon powder, may also be added.

Examples of silicone resins include methylsilicone resin,phenylmethylsilicone resin, alkyd-modified silicone resin andmelamine-modified silicone resin. Additives, such as aluminum powder forimproving heat resistance, may be added thereto.

Examples of fluororubbers include copolymers of trifluorochloroethyleneand vinylidene fluoride and copolymers of hexafluoropropylene andvinylidene fluoride.

Examples of fluorocarbon resins include polytetrafluoroethylene(Teflon), polytrifluorochloroethylene, copolymers of tetrafluoroethyleneand hexafluoropropylene, and polymers and copolymers of vinyl fluoride,vinylidene fluoride and dichlorodifluoroethylene.

The thickness of the coating of such releasable heat resistant polymersis not particularly limited, and the preferred thickness depends on thekinds of the releasable heat resistant polymers. In cases of siliconerubbers and fluororubbers, it is preferably 200 to 700 μm, morepreferably 300 to 500 μm. In cases of silicone resins and fluorocarbonresins, it is preferably 10 to 100 μm, more preferably 20 to 50 μm.

The projection on the surface of the radiation heater (or the surface ofthe laminate holder of the radiation heater) may also be formed bymaking a hole in the radiation heater, and inserting therein a pin whichpartially protrudes from the opening of the hole. Projections formed onthe metal surface of the radiation heater by molding or the like maywear readily. Forming projections by inserting pins in the holes made inthe radiation heater facilitates exchange of worn pins. The wear ofprojections and the number of pin-exchanges may be reduced by using pinsof hard materials, such as quenched steel. Pins having coating of theabove-described releasable heat resistant polymers may also be used. Theshapes of the hole and pin are not particular limited as far as aprojection of a uniform height protrudes from the opening of the hole onpressing.

When at least one member of the laminate is placed close to theradiation heater, the gap between the laminate and the radiation heaterfacing each other is preferably made as narrow as possible, for example,0.1 to 0.4 mm, preferably 0.2 to 0.4 mm.

For efficient heating by the radiant heat emitted by the radiationheater, the laminate to be bonded by thermal bonding preferably has ametal member as the member to be placed close to the radiation heater.The adhesive is not particularly limited, and may be selected fromvarious adhesives, such as solvent-vaporizing adhesives, thermosettingadhesives and hot melt adhesives, depending on the materials of themembers and the uses of the bonded products.

As a thermal bonding and an apparatus of an embodiment according to theinvention, a method and an apparatus for producing a brake shoe assemblyfor drum brakes of vehicles will be explained hereinafter. The brakeshoe for drum brakes is generally produced by bonding a friction liningto a metallic brake shoe body with an adhesive. The brake shoe bodygenerally comprises a shoe rim of an arcuate band form bent lengthwiseand a shoe rib protruding radially inwardly from the radially inner faceof the shoe rim. The friction lining generally has a uniform thickness,and is laminated on the radially outer face of the shoe rim of the brakeshoe body with an adhesive interposed therebetween, and heated andpressed to bond.

FIG. 1 is a partially perspective view illustrating a thermal bondingmethod and an apparatus of an embodiment according to the invention.FIG. 2 is a cross-section of the thermal bonding method and apparatus ofFIG. 1. In this embodiment, one member of the laminate 1 is the brakeshoe body 11, and another member is the friction lining 12 that islaminated on the radially outer face of the shoe rim 111 of the brakeshoe body 11 with the adhesive 13 interposed therebetween.

The brake shoe body 11 has the shoe rim 111 of an arcuate band form bentlengthwise and the shoe rib 112 that extends in a direction of thelength of the shoe rim 111 along the center of the width of the shoe rim111 and protrudes radially inwardly from the circular arc.

The brake shoe body 11 is formed of a metal, preferably an SPC steelsheet-pile, and other metals, such as aluminum or an aluminum alloy, mayalso be used.

The brake shoe body may be coated with a coating, such as a primer.Primer coating on brake shoe bodies is for rust prevention and corrosionprotection, and examples of primers are resins commonly used asadhesives. For example, a solution of an adhesive, such as a phenolresin adhesive or an epoxy resin adhesive, dissolved in a solvent, suchas methanol, methyl ethyl ketone or toluene, is applied to the brakeshoe body and then dried by removing the solvent with heat, to form aprimer coating on the surface of the brake shoe body.

The friction lining 12 forms the friction surface of the brake shoeassembly, and is made of nonmetallic materials. For example, thefriction lining 12 to be used in the invention may be made by mixingshort fibers, such as asbestos short fibers or glass fibers, with abinder thermosetting resin, and forming the mixture into a bent sheetwith pressure and heat.

The adhesive 13 is applied to the radially outer face of the shoe rim111 of the brake shoe body 11 and to the radially inner face of thefriction lining 12, and dried with hot blast. The shoe rim 111 and thefriction lining 12 are then laminated with the adhesive 13 interposedtherebetween, to form the laminate 1. The adhesive 13 is generally athermosetting adhesive, and preferred examples are phenolic resinthermosetting adhesives and epoxy resin thermosetting adhesives, whichare particularly resistive to impact, bending and peeling.

In the apparatus as shown in FIGS. 1 and 2, the radiation heater 2comprises the plate-like heater 21 and the plural laminate holders 22that are mounted on the heater 21 with their bases in contact with theheater 21. As shown in FIG. 3, in the heater 21 of this embodiment, theSUS-cartridge heater 211 is assembled in cast aluminum and has terminals212. Each laminate holder 22 has the bent face 221 capable of beingcovered by the radially inner face of the shoe rim 111, the narrowgroove 222 for receiving the shoe rib 112 without contacting the shoerib 112 with the laminate holder 22, and a supporting member which is ashoe rim supporter comprising six projections 4 formed on the bent face221. Each groove 222 is wider than the thickness of the shoe rib 112.

The degree of the curve of the bent face 221 may be such that the bentface 221 is received by the shoe rim 111 close to the radially innerface. In the apparatus as shown in FIGS. 1 and 2, circular arc of thebent face 221 has a smaller radius than that of the radially inner faceof the shoe rim 111, and the tops of the projections 4 of the sameheight contact the radially inner face of the shoe rim 111 to supportthe laminate 1.

Although the shoe rim supporter in the apparatus as shown in FIGS. 1 and2 comprises six linear projections 4, the number of the projections arenot limited, and the linear projections may be replaced by one or moreprojections for point-contact, such as hemispherical projections.

FIG. 2 shows the shoe rib 112 is inserted in the narrow groove 222 ofthe laminate holder 22 without contacting the inner walls of the groove,and the shoe rim supporter comprising the six projection 4 is inline-contact with the radially inner face of the shoe rim 111 to supportthe laminate 1. In FIGS. 1 and 2, although the base 223 of the narrowgroove 222 is bent as close to the base of the shoe rib 112 as possible,it may be flat or may be grooved completely to the base of the laminateholder 22 since the shoe rib is generally thin and can be uniformlyheated by radiation to the sides.

The pressing unit 3 has a pressing band 31, such as a band of a springmaterial, having a bent face capable of fitting with the surface of thefriction lining 12 of the laminate 1, and a pressing band holder 32supporting the pressing band 31. Both ends of the pressing band 31 aresupported by the pressing band holder 32, and the remaining pressingpart between both ends has spring-elasticity. The pressing unit 3 may beof one body which makes one combination with all of the plural laminateholders 22, or may be of plural bodies which make combinations with theplural laminate holders respectively. Although one pressing unit 3 isshown over only one laminate holder 22 in FIGS. 1 and 2, one pressingunit 3 is arranged over each laminate holder 22.

FIG. 4 is a partially elevational view of another embodiment of thelaminate holder usable in the apparatus of FIGS. 1 and 2. In the bentface 221 of the laminate holder 22 are made plural holes 224 having themajor arc cross-section and extending perpendicular to the bendingdirection. As shown in FIG. 5, the cylindrical pins 5 having a circularcross-section of the same radius as that of the major arc cross-sectionof the holes 224 are inserted in the holes 224. The pins 5 partiallyprotrude from the openings of the holes 224, to form projections 4. FIG.6 shows a partial side view of the laminate holder 22 before makingholes, FIG. 7 illustrates pins 5 being inserted in the holes 224 made inthe bent face 221 of the laminate holder 22. Making slits 51 in thesurface of the pins 5 as shown in FIG. 8 further reduces the contactarea between the projections and the shoe rim.

FIG. 9 is a partially elevational view of the laminate holder 22 havingplural holes 224 each having a circular opening in the bent face 221 andextending into the laminate holder 22, and FIG. 10 is a partial top viewof the laminate holder 22. The cylindrical pins 5 each with an endspherically machined are inserted in the holes 224 through the openingsin the bent face 221 in the directions of the arrows. As shown in FIG.11, the pins 5 partially protrude from the holes 224 to form projections4. The pins are preferably detachable to facilitate exchanging wornpins.

FIG. 12 is a cross-section of a supporting member of another embodimentusable in the apparatus of FIGS. 1 and 2. The bent face 221 of thelaminate holder 22 of this embodiment has a radius larger than that ofthe radially inner face of the shoe rim 111. Having a radius larger thanthat of the shoe rim 111, the bent face 221 linearly contacts with onlyboth ends of the shoe rim 111 to support the whole laminate 1. That is,in this embodiment, the bent face 221 of the laminate holder 22 itselfpartially works as the supporting member.

FIG. 13 is a perspective view of another embodiment of a laminate for abrake shoe. The brake shoe body 11′ for the brake shoe has a circulararc-shape with two ends nearly facing each other, and has a pair ofparallel shoe ribs 112′ extending from both side edges of the shoe rim111′ radially inwardly relative to the circular arc-shape. Each end 113′of the shoe rim 111′ is folded double radially inwardly relative to thecircular arc-shape to form an M-shape together with the shoe ribs 112′.Although two friction linings 12′ are laminated on the radially outerface of the shoe rim 111′ with the adhesive 13′ interposed between eachfriction lining 12′ and the shoe rim 111′, the number and shape of thefriction linings 12′ may be altered depending on the conditions of thefollowing heating and pressing and on the apparatus therefor. If theside edges of the shoe rim 111′ are rounded, the friction linings 12′are preferably laminated on only the flat area of the radially outerface of the shoe rim 111′ as shown in FIG. 14.

FIG. 15 is a cross-section illustrating the laminate of FIG. 14 beingheated by a method of an embodiment according to the invention. A pairof radiation heaters 2′ having respective flat faces are arranged sothat the flat faces are close to the outer sides of the shoe ribs 112′of the brake shoe body 11′ respectively, to heat the brake shoe body 11′with radiant heat. Plural projections 4′ on the flat faces of theradiation heater 2′ are in contact with the outer sides of the shoe ribs112′ to support the laminate 1′. While the laminate 1′ is being heatedin such a manner, the friction linings 12′ are pressed to the brake shoebody 11′ to bond them.

Hereinafter, the procedure of bonding a laminate with heat and pressureusing the apparatus of FIGS. 1 and 2 will be described. First athermosetting adhesive is applied to the radially outer face of the shoerim 111 of the brake shoe body 11 and to the radially inner face of thefriction lining 12, and then dried in a hot-blast furnace. The shoe rim111 and the friction lining 12 are then laminated with the driedthermosetting adhesive interposed therebetween, to prepare the laminate1.

Subsequently, as the white arrow indicates in FIG. 1, the shoe rib 112of the brake shoe body 11 of the laminate 1 is inserted in the narrowgroove 222 of the laminate holder 22 so that it does not contact thewalls of the narrow groove 222. Plural projections 4, which construct ashoe rim supporter, on the bent face 221 of the laminate holder 22 comein line-contact with the radially inner face of the shoe rim 111, tosupport the laminate 1. The pressing unit 3 descends in the direction ofthe white arrow to approach the laminate 1, and the pressing band 31comes in contact with the surface of the friction lining 12 and pressesthe laminate 1. At the time, the shoe rim 111 and the friction lining 12are pressed and bonded to each other with the adhesive 13 by thepressing band 31 uniformly in the whole bonding interface. The pressureis generally 7 kg/cm² or more, preferably 7 to 30 kg/cm². The heatingtemperature depends on the kind of the adhesive, and the preferredtemperature is generally such that the shoe rim 111 and the shoe rib 112are heated by radiant heat to 220 to 300° C. for 2 to 5 minutes. Thetime of heating and pressing depends on, for example, the temperature ofthe laminate holder 22, the material of the brake shoe body 11, the kindof the adhesive and the gaps separating the laminate holder 22 from theradially inner face of the shoe rim 111 and the sides of the shoe rib112. When the brake shoe body 11 is formed of SPC steel, the shoe rim111 is 1.4 to 2.6 mm thick, the shoe rib 112 is 3.2 to 4.5 mm thick, thegaps separating the laminate holder 22 from the radially inner face ofthe shoe rim 111 and the sides of the shoe rib 112 are 0.1 to 0.4 mm,and the temperature of the laminate holder 22 is 220 to 300° C.,generally, the friction lining 12 can be bonded strongly to the shoe rim111 by heating and pressing for 2 to 5 minutes.

After bonding, the pressing unit 3 ascends and moves away from thelaminate 1 in the opposite direction to the arrow, to stop applyingpressure to the laminate 1.

EXAMPLE 1

Brake shoe bodies formed of SPC steel (thickness of shoe rim: 1.6 mm,thickness of shoe rib: 3.2 mm) and friction linings were bondedrespectively by using the apparatus as shown in FIG. 1. The frictionlinings used are an asbestos lining, which was produced by curing amixture of asbestos fiber, a phenolic resin binder, a lubricant and afriction controlling agent with pressure and heat, and a non-asbestoslining, which was produced by curing a mixture of glass fiber, organicfiber, a phenolic resin binder, a lubricant and a friction controllingagent with pressure and heat. CEMEDINE CS2711 (trade name,nitrile-modified phenolic resin produced by Cemedine Co., Ltd.) was usedas an adhesive. The laminate holder used was formed of aluminum andcoated black. The bent face of the laminate holder was heated to 270°C., and a laminate produced by laminating the brake shoe body and thefriction lining with the adhesive interposed therebetween was mounted onthe laminate holder (the gap between the bent face of the laminateholder and the radially inner face of the shoe rim, namely the height ofthe projections: 0.2 mm; the gap between the side walls of the narrowgroove and the sides of the shoe rib: 0.4 mm), and was heated andpressed for 3.5 minutes at a pressure of 20 kg/cm². The temperature ofthe brake shoe body rose to 260° C. for two minutes after the beginningof pressing and heating, and was then almost uniform at 260° C. Bymeasurements of the bonding strength between the friction linings andthe brake shoe bodies in the product brake shoe assemblies, both theasbestos lining and the non-asbestos lining were found bonded stronglywith a shear strength of 16.8 kN.

INDUSTRIAL APPLICABILITY

By using the thermal bonding method and apparatus of the invention,bonding with heat and pressure using adhesives, such as bonding shoe rimof brake shoe body and friction lining, can be performed speedily withgood heating efficiency, and plural bonded products can be producedcontinuously by using simple equipment. Further, since heating is notperformed by heat conduction from a heater but by radiant heat emittedfrom a heater, any coating on coated laminates is not peeled off nortransfer to the heater. Accordingly, the method and apparatus of theinvention are particularly suitable for bonding coated members withadhesives by heating and pressing.

What is claimed is:
 1. A thermal bonding method for bonding at least twomembers to each other with an adhesive by pressing and heating alaminate formed by laminating the members on each other with theadhesive interposed therebetween, comprising: placing at least onemember of the laminate close to a heated radiant heater, and pressingthe laminate, in a state where radiant heat is applied to portions ofthe at least two members being bonded, wherein the radiant heatercomprises a heater element and a laminate holder which is in contactwith the heater element, with heat transferred from the heater elementto the laminate holder by heat conduction, the laminate holder emittingradiant heat to the laminate, the laminate holder coming inpoint-contact or line-contact with the at least one member of thelaminate so that the laminate is supported by the laminate holder and ispressed in the radiant heat-applied state, wherein one member of thelaminate is a brake shoe body, which comprises a shoe rim of an arcuateband form bent lengthwise and a shoe rib protruding radially inwardlyfrom a radially inner face of the shoe rim, another member of thelaminate is a friction lining laminated on a radially outer face of theshoe rim of the brake shoe body with the adhesive interposedtherebetween, and wherein the brake shoe body is placed close to theradiant heater.
 2. The method of claim 1, wherein plural laminates arebonded simultaneously using plural laminate holders by supporting eachlaminate by a respective laminate holder with at least one member of thelaminate placed close to and partially in contact with the laminateholder, and the laminate being pressed in the radiant heat-appliedstate.
 3. The method of claim 1, wherein at least one member of thelaminate is heated to 220 to 300° C. with the radiant heat, and thelaminate is pressed at a pressure of 7 kg/cm² or more.
 4. The method ofclaim 1, wherein the brake shoe body comprises a shoe rim of an arcuateband form bent lengthwise and a shoe rib, which protrudes radiallyinwardly from a radially inner face of the shoe rim and extends in adirection of the length of the shoe rim along center of the width of theshoe rim.
 5. The method of claim 1, wherein the brake shoe body iscoated with a primer.
 6. The method of claim 1, wherein the radiantheater has a black surface.
 7. The method of claim 1, wherein thelaminate holder has projections on the surface thereof, for thepoint-contact or line-contact with the at least one member of thelaminate.
 8. The method of claim 7, wherein the projections are of asize such that the at least one member of the laminate is spaced 0.1 to0.4 mm from the surface of the laminate holder.
 9. An apparatus forbonding at least two members to each other with an adhesive by pressingand heating a laminate formed by laminating the at least two memberswith the adhesive interposed therebetween, comprising a radiant heater,a supporting member for supporting the laminate so that at least onemember of the at least two members is placed close to the radiantheater, and a pressing unit adapted to approach, contact and press thelaminate supported by the supporting member and then move away from thelaminate to stop applying pressure to the laminate, the radiant heaterincluding a heater element and a laminate holder, the laminate holderbeing in contact with the heater element to transfer heat, from theheater element to the laminate holder, by heat conduction, the laminateholder emitting radiant heat for heating portions of the at least twomembers to be bonded, and having the supporting member and a faceadapted to be close to the at least one member of the laminate, and thesupporting member being formed on the face of the laminate holder sothat when the at least one member is placed close to the face of thelaminate holder the supporting member comes in point-contact orline-contact with the at least one member to support the laminate,wherein one member of the laminate is a brake shoe body, which comprisesa shoe rim of an arcuate band form bent lengthwise and a shoe ribprotruding radially inwardly from a radially inner face of the shoe rim,and another member of the laminate is a friction lining laminated on aradially outer face of the shoe of brake shoe body with the adhesiveinterposed therebetween, wherein the supporting member is adapted tosupport the laminate, with the brake shoe body placed close to theradiant heater, and wherein the pressing unit is adapted to approach andcontact the surface of the friction lining of the laminate supported bythe supporting member and press the laminate, and them move away fromthe laminate to stop applying pressure to the same.
 10. The apparatus ofclaim 9, wherein the radiant heater comprises the heater and plurallaminate holders contacting the heater, and the pressing unit is adaptedto press plural laminates supported by the laminate holderssimultaneously.
 11. The apparatus of claim 9, wherein the brake shoebody comprises a shoe rim of an arcuate band form bent lengthwise and ashoe rib, which protrudes radially inwardly from a radially inner faceof the shoe rim and extends in a direction of the length of the shoe rimalong center of the width of the shoe rim.
 12. The apparatus of claim11, wherein the pressing unit has a pressing band having a bent facecapable of fitting with the surface of the friction lining of thelaminate, and a pressing band holder which supports the pressing band.13. The apparatus of claim 11, wherein the radiation heater comprises aheater and a laminate holder contacting the heater to conduct heat fromthe heater and emit radiant heat and having the supporting member and aface capable of being close to the brake shoe body of the laminate, andwherein the supporting member is formed on the face of the laminateholder so that when the at least one member is placed close to the faceof the laminate holder, the supporting member comes partially in contactwith the brake shoe body to support the laminate.
 14. The apparatus ofclaim 13, wherein the laminate holder has a bent face and a narrowgroove, the bent face being capable of fitting with the radially innerface of the shoe rim and having a radius larger than a radius of theradially inner face of the shoe rim, the narrow groove being forreceiving the shoe rib without contacting the shoe rib, and wherein thebent face works as the supporting member at a part where the bent facecontacts the shoe rim when the laminate is supported by the laminateholder, with the radially inner face of the shoe rim is placed close tothe bent face of the laminate holder, and with the shoe rim received inthe narrow groove.
 15. The apparatus of claim 9, where the face isblack.
 16. The apparatus of claim 9, wherein the supporting member isprojections extending from the face of the laminate holder, for thepoint-contact or line-contact with the at least one member of thelaminate.
 17. The apparatus of claim 16, wherein the projections are ofa size such that the at least one member of the laminate is spaced 0.1to 0.4 mm from the surface of the laminate holder.
 18. An apparatus forbonding at least two members to each other with an adhesive by pressingand heating a laminate formed by laminating the two members with theadhesive interposed therebetween, comprising a radiant heater, asupporting member for supporting the laminate so that at least onemember of the at least two members is placed close to the radiantheater, and a pressing unit adapted to approach, contact and press thelaminate supported by the supporting member and then move away from thelaminate to stop applying pressure to the laminate, the radiant heaterincluding a heater element and a laminate holder, the laminate holderbeing in contact with the heater element to transfer heat, from theheater element to the laminate holder, by heat conduction, the laminateholder emitting radiant heat and having the supporting member and a faceadapted to be close to the at least one member of the laminate, and thesupporting member being formed on the face of the laminate holder sothat when the at least one member is placed close to the face of thelaminate holder such that the supporting member comes in point-contactor line-contact with the at least one member to support the laminate,wherein one member of the laminate is a brake shoe body which comprisesa shoe rim of an arcuate band form bent lengthwise and a shoe ribprotruding radially inwardly from a radially inner face of the shoe rim,and another member of the laminate is a friction lining laminated on aradially outer face of the shoe rim of the brake shoe body with theadhesive interposed therebetween; wherein the supporting member isadapted to support the laminate, with the brake shoe body placed closeto the radiant heater; wherein the pressing unit is adapted to approachand contact the surface of the friction lining of the laminate supportedby the supporting member and press the laminate, and them move away fromthe laminate to stop applying pressure to the same; wherein the brakeshoe body comprises a shoe rim of an arcuate band form bent lengthwiseand a shoe rib, which protrudes radially inwardly from a radially innerface of the shoe rim and extends in a direction of the length of theshoe rim along a center of the width of the shoe rim; wherein theradiation heater comprises a heater and a laminate holder contacting theheater to conduct heat from the heater and emit radiant heat and havingthe supporting member and a face capable of being close to the brakeshoe body of the laminate; wherein the supporting member is formed onthe face of the laminate holder so that when the at least one member isplaced close to the face of the laminate holder, the supporting membercomes partially in contact with the brake shoe body to support thelaminate; wherein the laminate holder has a bent face and a narrowgroove, the bent face being capable of fitting with the radially innerface of the shoe rim, the narrow groove being for receiving the shoe ribwithout contacting the shoe rib; and wherein the supporting member is ashoe rim supporter comprising at least one projection formed on the bentface of the laminate holder.
 19. The apparatus of claim 18, wherein thesurface of the projection on the bent face is coated with a releasableheat resistant polymer.
 20. The apparatus of claim 18, wherein a pin isinserted in a hole made in the laminate holder so that a part of the pinprotrudes from the bent face to form the projection.